Loopback configurations are often used to calibrate and test integrated circuits. For example, a master component or circuit may send data and/or clock signals to a slave component to calibrate the slave component with respect to the master component (e.g., often referred to as “training”), where the responses received by the master component from the slave component indicate whether or not the slave component is calibrated. Additionally, this training using the loopback configuration can be performed periodically to recalibrate the system and compensate for variations (e.g., process variations, voltage variations, temperature variations, etc.) which occur over time. Loopback configurations may also be used to test or verify a slave component by sending test data (e.g., test vectors or patterns) to the slave component and comparing received responses with expected values to validate the operation of the slave component.
Some conventional loopback configurations utilize multiple dedicated unidirectional interfaces for sending the training data or test data between the master and slave components. For example, a first interface is used to send the data from the master component to the slave component, whereas a second interface is used to send data from the slave component to the master component. As such, each interface has a fixed (e.g., predetermined and unchangeable) direction of data communication.
Although conventional loopback configurations using multiple unidirectional interfaces enable integrated circuit calibration and testing, the results of the testing and the effectiveness of the calibration is limited. For example, the use of multiple interfaces makes it more difficult to isolate problems that may exist on one of the multiple interfaces. Additionally, since multiple interfaces are required to calibrate the system, the interfaces cannot be calibrated separately. As such, additional calibration steps are required to account for all the possible loopback configurations, where each configuration utilizes a different combination of interfaces and/or interface components (e.g., required to link the interfaces and implement the loopback). Further, the fixed master/slave relationship and the fixed direction of data communication between the components further limits the calibration and testing of the system and components thereof.
Other conventional loopback configurations use multiple bi-directional interfaces for communicating data between master and slave components. Conventional bi-directional interfaces comprise multiple paths or lanes, where each lane is capable of communicating information in either a forward or reverse direction depending upon the current configuration of each respective lane. Additionally, conventional bi-directional interfaces configure all lanes to communicate information in the same direction (e.g., all in the forward direction or all in the reverse direction), thereby operating similarly to a dedicated unidirectional interface at any given instant in time. As such, conventional loopback configurations using multiple bi-directional interfaces operate similarly to the conventional loopback configurations utilizing multiple unidirectional interfaces. Thus, conventional loopback configurations using multiple bi-directional interfaces suffer drawbacks similar to those discussed above with respect to conventional loopback configurations utilizing multiple unidirectional interfaces.